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Description

Scientific instrumentation is a traditionally expensive area. At the dawn of the millennium John Alexander published a design which brought scanning tunnelling microscopy (STM) to an affordable level. Using a standard piezo transducer it is possible to examine materials on an atomic scale. This project aims to build on his work and digitize the analogue system, providing more advanced data collection and visualization.

Components

Project Logs

It seems as though I have been beaten to it and Hackaday have recently published a post about this project with atomic resolution! I shall persevere with my own and try to pull in changes from that one.

Apologies for the lack of work over the last few months. I have been starting my PhD on microwave metrology and it has taken a lot of my time. However, I have now acquired an enclosure for the microwscope (an old 3U eurocard chassis from a vacuum controller). My plan is to have half the chassis taken up by signal conditioning and perhaps an embedded computer and display, with the rest of the chassis containing a slide-out tray with the sample stage and probe.

I am going to order the parts to make the analog version linked to on this page, get that working and then start the modifications.

For a microscope that involves tracking an atom-thick tip across nanometres of surface, vibrations are not good. STMs often utilize very nice anti-vibration techniques which vary in cost and complexity from simple mechanical dampers to active air or magnetic levitation systems.

For this project I want to explore the possibility of an active vibration-cancelling system, potentially using a continuous 12v air blower to provide a smooth supply of air pressure to actuators mounted on the instrument stage (like the one shown below). The actuators would be 3d printed and use a design which kept the stage supports floating centrally in the stream so as not to make contact with the base at all. If this did not work, then magnets could be used to centre the supports or float the entire stage itself. The weight should be rather small as it only needs to hold a piezo, sample and cantilever.